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hershey8

Slop bucket clay seems a little bit "short."

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  I recently pugged some  bits of clay from my slop bucket. The pug comes out reasonably soft and moist, but kind of cracky. It is all the same type of clay, well 99% anyway. Whassup with dat?   j

 

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Good question!

At the local Junior College, the reclaimed clay throws ok up to a point, then turns into Thing's face

image.png.51586ab42379f8c08998b82aa868da65.png

which can be saved with some ribbing; for handles, it just don' behave very well - it pulls up to a point, then just separates (no "legs"?).

However, reclaimed clay at home is working very well for me, not sure why - different clay, and the process a bit different as well. At home I thoroughly dry out all the ooops, trimmings and such, then re-slake; the slop is just tossed in after pouring off the clear water. Then I woosh it with the big drill motor and grout mixer. Finally, once dry enough, the mush hits the plaster bats for final drying before wedge and bag. For sure each bit of clay is wet for several weeks after the re-slake.

At school, not sure what they do.

Edited by Hulk
+ a word

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1 hour ago, Hulk said:

the slop is just tossed in

+1 for this. The throwing water plus the slip/slop in the splashpan contains the fines. Since the smaller the clay particles the more plastic the clay is by adding the fines back to the clay it will help with restoring the plasticity to the clay. If you don't have enough throwing slip/splashpan slop to fix a short body you can add some ball clay, won't take much. (or blunged bentonite or macaloid if you are using porcelain) If your pugger has a vacuum that helps get the water in=between the clay particles to wet the small (plastic) particles, if not then pugging the clay on the wet side and letting it sit for a couple weeks will help also.

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9 hours ago, Hulk said:

Good question!

At the local Junior College, the reclaimed clay throws ok up to a point, then turns into Thing's face

image.png.51586ab42379f8c08998b82aa868da65.png

which can be saved with some ribbing; for handles, it just don' behave very well - it pulls up to a point, then just separates (no "legs"?).

However, reclaimed clay at home is working very well for me, not sure why - different clay, and the process a bit different as well. At home I thoroughly dry out all the ooops, trimmings and such, then re-slake; the slop is just tossed in after pouring off the clear water. Then I woosh it with the big drill motor and grout mixer. Finally, once dry enough, the mush hits the plaster bats for final drying before wedge and bag. For sure each bit of clay is wet for several weeks after the re-slake.

At school, not sure what they do.

I've been throwing flopped pot pieces and trimmings into a big container and misting.  Did not slake. Maybe that's the problem.

 

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When it comes to scraps-they are different if dried. The fines that Min talks about are also a key component. I never pug dry clay scraps-but thats with porcelain.Stoneware is more forgiving.I only add my wet clay to pugged clay.

If you want better results with dry rewetted clay add the fines and a little vinegar -pug it and let it sit for a few months. It will never have the legs (meaning throws better)as original clay but it will throw better that what you have now.

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54 minutes ago, hershey8 said:

I've been throwing flopped pot pieces and trimmings into a big container and misting.  Did not slake. Maybe that's the problem.

 

I don't think so. Dry clay slakes down far quicker than trying to re-wet semi moist clay but those fine particles still need to get wetted down which takes time. By not letting your clay dry out the fines are already wetted. 

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Every time you work clay, fine particles are washed away in the throwing water. If that water isn't added back into the slop, the fine particles are missing. As  Min said, those are the particles that add plasticity. But you're also losing other ingredients, too, like the fluxes and silica. After you've reclaimed the slop a couple times, you've really got a clay body that is different than the original and may not fire to vitrification any more. The best way to deal with recycling is to make sure all the throwing water and slop in the splash pan goes into the slop buckets as well. If you need to add dry material, it's best to add a dry mix of the clay body you're using. Just adding ball clay can mess things up over time. Most clay manufacturers will sell dry mixes of their clay bodies.

When I was the tech for A.R.T. Clay, I would regularly get phone calls from schools whose clay stopped working for them, usually in the way of glazes shivering off the white earthenware. They were pugging the reclaim with straight ball clay, and after a few rounds the body was all messed up, with too much clay and not enough talc. Their only solution was to start over with new clay, since we didn't know how much of anything was actually in the body anymore. So they would buy new moist clay, and a few bags of dry mix for recycling.

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1 hour ago, neilestrick said:

If you need to add dry material, it's best to add a dry mix of the clay body you're using. Just adding ball clay can mess things up over time. Most clay manufacturers will sell dry mixes of their clay bodies.

To help prevent our reclaim from throwing short, we buy 50lb bags of dry mix of one of our clays and add a big scoop of the powder directly into the pugmill with each batch we mix/pug. Each bag lasts a long time and it has really helped the quality of our reclaim.

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Sometimes I've noticed the recycled clay being short, I use it for small pots...

The local supplier doesn't sell the dry clay mix. 

Would the short clay cause cracking problems with small 4"x 4"  terracota slabs?

Thanks

 

 

Edited by enbarro

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So ,  ideally, I should let all scrap clay dry out completely,  pulverize to some degree, (working on a machine for that), add water and maybe some slop/slip of the same clay body with some vinegar. Mix , slake and pug.Let set for a couple of weeks and see how it works? Am I missing  anything? Should I  make  some slip from new clay and add that? If the clay scraps are really small and very dry, how long does it really need to slake?    ja

 

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I can't really see drying out new clay just to slake it down, and wouldn't want the dust from pulverizing it. If you do want to add unused clay, and can't get it powdered, I would just use it straight from the box and mix it with your wet scrap in the pugger, run it through a couple times to get it blended together and try it. (try bending a coil around your finger, clay shouldn't crack) If it's still not plastic enough I would leave it for a couple weeks and see if it's improved. If it's still short I would add more fresh unused clay and try again. 

Edited by Min

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So far I've solved my shortness issues by soaking clay for a few days or longer without ever drying it out fully. However I've noticed if I do this without a particular trick results are varied. BTW I got this idea off a Simon Leach video so if you think it's unnecessary blame him, but it works for me. What I do is use a long knitting needle or somesuch to poke holes all the way through the clay, pour a cup or two of water over it, drop the bag into a bucket of water to squeeze all the air out, and let sit for at least 12 hours. This works perfectly for new blocks that are too dry or have been sitting around my place too long. 

 I wasn't aware of saving the 'smalls' water until now so my first slop bucket recycle might be interesting and maybe I'll try drying out some bag clay and pound it up to add back. 

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If its stoneware it will get wet easy so no need to dry it out more just add water. Porcelains are another story.

stoneware is easy to rewet. add some fines from your splash pan . Thats what I use to make my joining slip for handles-it works the best.

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17 hours ago, enbarro said:

The local supplier doesn't sell the dry clay mix. 

Our supplier (Vermont Ceramic Supply) doesn't stock the dry clay mix either, but they order it from Laguna for us whenever we need it. I'd ask your supplier... my guess is that it'll be an easy request to fulfill.

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9 hours ago, Min said:

I can't really see drying out new clay just to slake it down, and wouldn't want the dust from pulverizing it. If you do want to add unused clay, and can't get it powdered, I would just use it straight from the box and mix it with your wet scrap in the pugger, run it through a couple times to get it blended together and try it. (try bending a coil around your finger, clay shouldn't crack) If it's still not plastic enough I would leave it for a couple weeks and see if it's improved. If it's still short I would add more fresh unused clay and try again. 

Thank you Min,  I may be over thinking this. But n the future I will begin saving  my scrap a differently, not tossing throwing water or fines.   I will save it all in a bucket.  Today, I'll start pugging the old with the new. I'm sure that will work. Thank you for your help.   ja

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2 hours ago, Chris Throws Pots said:

Our supplier (Vermont Ceramic Supply) doesn't stock the dry clay mix either, but they order it from Laguna for us whenever we need it. I'd ask your supplier... my guess is that it'll be an easy request to fulfill.

Thanks, Chris!

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